Peanut arachidin-1 enhances Nrf2-mediated protective mechanisms against TNF-α-induced ICAM-1 expression and NF-κB activation in endothelial cells.

Arachidin-1 [trans-4-(3-methyl-1-butenyl)-3,5,3',4'-tetrahydroxystilbene] is a polyphenol produced by peanut kernels during germination. The aim of the present study was to investigate the mechanism underlying the anti-inflammatory effect of arachidin-1 in endothelial cells (ECs). The results of cell adhesion and western blotting assays demonstrated that arachidin-1 attenuated tumor necrosis factor (TNF)-α-induced monocyte/EC adhesion and intercellular adhesion molecule-1 (ICAM-1) expression. Arachidin-1 was demonstrated to exert its inhibitory effects by the attenuation of TNF-α-induced nuclear factor-κB (NF-κB) nuclear translocation and inhibitor of κB-α (IκBα) degradation. Furthermore, arachidin-1 upregulated nuclear factor-E2-related factor-2 (Nrf-2), a known mediator of phase II enzyme expression, and increased the transcriptional activity of antioxidant response element. Transfection of ECs with Nrf-2 siRNA blocked the inhibitory effect of arachidin-1 on ICAM-1 expression, NF-κB nuclear translocation and IκBα degradation. In addition, arachidin-1 induced the expression of the phase II enzymes thioredoxin-1, thioredoxin reductase-1, heme oxygenase-1, glutamyl-cysteine synthetase and glutathione S-transferase. Following arachidin-1 pretreatment, the H2O2-induced generation of reactive oxygen species was reduced. Therefore, the present results indicate that arachidin-1 suppresses TNF-α-induced inflammation in ECs through the upregulation of Nrf-2-related phase II enzyme expression.